Angle sensor having low waveform distortion

ABSTRACT

A magnetoresistive element includes a meandering X-axis array that is constituted by X-axis segments alternately connected, and a meandering Y-axis array that is constituted by Y-axis segments alternately connected. When rotated 90°, the Y-axis array has the same layout as the X-axis array. Such a structure cancels the electrical resistance change due to the AMR effect, thus reducing the waveform distortion of output voltage.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.10/879,674 (Attorney Docket No. ALPSP160) filed on Jun. 28, 2004, byinventors Sudo et al. and entitled “ANGLE SENSOR HAVING LOW WAVEFORMDISTORTION,” which is incorporated herein by reference for all purposes.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an angle sensor including amagnetoresistive element, such as a GMR element, and particularly to anangle sensor that can reduce the waveform distortion of output voltage.

2. Description of the Related Art

Angle sensors including magnetoresistive elements are already known(see, for example, Japanese Unexamined Patent Application PublicationNo. 2002-303536).

The magnetoresistive element is a laminate that essentially consists ofan antiferromagnetic layer, a pinned magnetic layer, a nonmagneticmaterial layer, and a free magnetic layer. The pinned magnetic layer isunidirectionally magnetized by a coupling magnetic field generatedbetween the pinned magnetic layer and the antiferromagnetic layer. Themagnetization of the free magnetic layer varies under an externalmagnetic field.

The angle sensor may be provided with a rotor having a magnet over themagnetoresistive element. The rotation of the rotor changes thedirection of a magnetic flux flowing into the laminate from the magnet.

The magnetization of the free magnetic layer varies with the directionof the magnetic flux, and thereby the electrical resistance andtherefore the output voltage of the magnetoresistive element vary. Theangle sensor detects the rotation angle based on the change in theoutput voltage.

FIG. 7 shows a magnetoresistive element for use in a conventional anglesensor.

Two magnetoresistive elements 2 and 3 are disposed on a substrate 1.Each end of the magnetoresistive elements 2 and 3 is connected to a lead4, 5, 6, or 7 made of Au or the like. The leads 4, 5, 6, and 7 haveterminals 8-15 at their opposite ends.

Four substrates 1, for example, are disposed below the rotor. Anymagnetoresistive elements on the substrates 1 are connected to oneanother to form a Wheatstone bridge.

The magnetoresistive elements 2 and 3 extend in the X-axis direction(the width direction of the substrate 1), and meander in the Y-axisdirection (the depth direction of the substrate 1), thus forming asingle zigzag structure.

The electrical resistance of the magnetoresistive element is expressedby the following equation:R _(g) =R _(g0) −ΔR _(g) cos θ  (1)wherein R_(g) is an electrical resistance of the magnetoresistiveelement, R_(g0) is a center resistance, ΔR_(g) is an amplitude of theelectrical resistance change, and θ is an angular difference in themagnetization direction between the pinned magnetic layer and the freemagnetic layer.

To obtain a theoretical waveform of output voltage, the magnetizationdirection of the pinned magnetic layer should be independent of theexternal magnetic field, and the magnetization direction of the freemagnetic layer should be identical to the direction of the externalmagnetic field. However, in practice, the magnetization direction of thefree magnetic layer is not identical to the direction of the externalmagnetic field. This, in combination with other factors, causes themeasured waveform of output voltage to deviate slightly from thetheoretical waveform.

FIG. 8 shows a waveform of the output voltage generated by the rotationof a rotor that has a magnet and faces the substrate 1 in FIG. 7. Themeasured waveform of output voltage deviates from the theoreticalwaveform.

Such a distortion of the waveform may partly result from AMR(anisotropic magnetoresistance) effect, which is illustrated in FIG. 9.When an electric current runs through a GMR element aligned in theX-axis direction, and a free magnetic layer is magnetized at an angle ofθ′, the AMR effect is expressed by the following equation:R _(A) =R _(A0) +ΔR _(A) cos²⁰′  (2)wherein R_(A) is a contributing resistance by the AMR effect, R_(A0) isa center resistance, ΔR_(A) is an amplitude of the contributingresistance change, and θ′ is an angle between the current direction andthe magnetization direction of the free magnetic layer.

As is apparent from equation 2, R_(A) changes with θ′ This AMR effectcauses variations in R_(g) in equation 1, and thus the waveformdistortion cannot be reduced.

Another factor in the waveform distortion is a magnetic field having ashape anisotropy. The magnetic shape anisotropy is a property thatmagnetization tends to be oriented longitudinally, for example, alongthe X-axis of the magnetoresistive element 2 or 3 in FIG. 7.

FIG. 10 illustrates a deviation in the magnetization direction in thefree magnetic layer, caused by the shape anisotropic magnetic field.Considering the shape anisotropic magnetic field H_(k), themagnetization direction θ″ of the free magnetic layer is expressed bythe following equation: $\begin{matrix}{\theta^{\prime\prime} = {{TAN}^{- 1}\frac{H_{k} + {H_{0}{SIN}\quad\theta}}{H_{bf} + {H_{0}{COS}\quad\theta}}}} & (3)\end{matrix}$wherein H₀ is an external magnetic field, H_(k) is a shape anisotropicmagnetic field, H_(bf) is a bias magnetic field, θ is an externalmagnetic field direction, and θ″ is a magnetization direction of a freemagnetic layer.

Ideally, as described above, the magnetization direction of the freemagnetic layer is identical to that of the external magnetic field H₀.However, as shown in FIG. 10, the shape anisotropic magnetic fieldH_(k), as well as the bias magnetic field H_(bf), causes the angle θ″ ofthe free magnetic layer (the angle θ″ is an inclination from the Y-axis)to deviate from the angle θ of the external magnetic field H₀.

Thus, to minimize the deviation, the shape anisotropic magnetic fieldH_(k) is preferably as small as possible.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide anangle sensor that exhibits a smaller waveform distortion of the outputvoltage than conventional angle sensors by the reduction of the AMReffect and the influence of the shape anisotropic magnetic field.

In one aspect, the present invention provides an angle sensorcomprising:

a magnetoresistive element that includes a pinned magnetic layer havinga fixed magnetization direction and a free magnetic layer having amagnetization direction that varies in proportion to an externalmagnetic field;

a substrate for supporting the magnetoresistive element; and

a rotor that forms a magnetic field and faces the magnetoresistiveelement,

wherein the magnetoresistive element includes an X-axis array in anX-axis direction being the width direction of the substrate and a Y-axisarray in a Y-axis direction being the depth direction of the substrate,the X-axis array including a plurality of segments that extend in theX-axis direction and are spaced at a predetermined interval in theY-axis direction, the predetermined interval being shorter than thelength of the X-axis segments, ends of adjacent X-axis segments beingconnected so as to form a single meandering structure, the Y-axis arrayincluding a plurality of segments that extend in the Y-axis directionand are spaced at a predetermined interval in the X-axis direction, thepredetermined interval being shorter than the length of the Y-axissegments, ends of adjacent Y-axis segments being connected so as to forma single meandering structure, and the magnetoresistive element has asingle continuous structure in which the X-axis array and the Y-axisarray are connected to each other at their ends.

In the aspect described above, the X-axis array and the Y-axis arrayhave meandering structures, and the Y-axis array, when rotated 90°, hasthe same layout as the X-axis array.

Such a structure cancels the electrical resistance change caused by theAMR effect in the free magnetic layer, thus reducing the waveformdistortion of the output voltage.

Preferably, the X-axis segments and the Y-axis segments have the samedimensions. This efficiently cancels the changes in the contributingresistance generated by the AMR effect in the free magnetic layer.

In another aspect, the present invention provides an angle sensorcomprising:

a magnetoresistive element that includes a pinned magnetic layer havinga fixed magnetization direction and a free magnetic layer having amagnetization direction that varies in proportion to an externalmagnetic field;

a substrate for supporting the magnetoresistive element; and

a rotor that forms a magnetic field and faces the magnetoresistiveelement,

wherein the magnetoresistive element includes a plurality of X-axissegments that extend in an X-axis direction being the width direction ofthe substrate, and a plurality of Y-axis segments that extend in aY-axis direction being the depth direction of the substrate, the X-axissegments and the Y-axis segments having the same length and width, andbeing alternately connected to each other to form a single continuousstructure.

Such a structure cancels the electrical resistance change caused by theAMR effect in the free magnetic layer, thus reducing the waveformdistortion of the output voltage.

Preferably, each of the Y-axis segments is connected to each verticalsurface of the X-axis segments, and each of the X-axis segments isconnected to each horizontal surface of the Y-axis segments, so that themagnetoresistive element forms at least one row extending in the X-axisdirection or the Y-axis direction, and each end of the rows in the samedirection is alternately connected to form a single continuousstructure, when said at least one row comprises a plurality of rows.

Such a structure allows the magnetoresistive element to be arrangedefficiently on the narrow substrate. In general, the substrate has apredetermined size, depending on the situation, and the electricalresistance of the magnetoresistive element on the substrate (under theexternal magnetic field perpendicular to the magnetization direction ofthe pinned magnetic layer) is standardized to have a constant value. Inthis situation, when the magnetoresistive element including the X-axissegments and the Y-axis segments is provided on the substrate, themagnetoresistive element is preferably formed as a single continuousstructure by connecting each end of the rows to reduce the changes inthe contributing resistance due to the AMR effect.

In still another aspect, the present invention provides an angle sensorcomprising:

a magnetoresistive element that includes a pinned magnetic layer havinga fixed magnetization direction and a free magnetic layer having amagnetization direction that varies in proportion to an externalmagnetic field;

a substrate for supporting the magnetoresistive element; and

a rotor that forms a magnetic field and faces the magnetoresistiveelement,

wherein the magnetoresistive element includes a plurality of segments inan X-axis direction being the width direction of the substrate and aplurality of segments in a Y-axis direction being the depth direction ofthe substrate, the X-axis segments being spaced at a predeterminedinterval in the Y-axis direction, the Y-axis segments being spaced at apredetermined interval in the X-axis direction, the X-axis segments andthe Y-axis segments being the same in number, length, and width.

Such a structure cancels the electrical resistance change caused by theAMR effect in the free magnetic layer, thus reducing the waveformdistortion of the output voltage.

Preferably, the X-axis segments and the Y-axis segments have a width of20 μm or more, and the ratio of length to width is less than 11.

Preferably, the X-axis segments and the Y-axis segments have a width ofmore than 20 μm, and the ratio of length to width is 11 or less.

Such restrictions on the dimensions of the magnetoresistive elementreduce the deviation of the magnetization of the free magnetic layercaused by the shape anisotropic magnetic field Hk, bringing themagnetization close to the external magnetic field direction, andthereby the waveform distortion of the output voltage can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a rotation angle sensor according tothe present invention;

FIG. 2 is an enlarged plan view of a substrate that comprises amagnetoresistive element according to the present invention and is to bemounted on the sensor shown in FIG. 1;

FIG. 3 is an enlarged plan view of a substrate that comprises amagnetoresistive element according to another embodiment of the presentinvention;

FIG. 4 shows some layouts of magnetoresistive elements mounted onsubstrates;

FIG. 5 shows circuit diagrams of a rotation angle sensor according tothe present invention;

FIG. 6 is a fragmentary isometric sectional view of a magnetoresistiveelement;

FIG. 7 is a plan view of a magnetic detector mounted on a conventionalrotation angle sensor;

FIG. 8 is a graph showing a waveform of output voltage measured with themagnetoresistive element shown in FIG. 7 and a waveform of outputvoltage obtained from theoretical values;

FIG. 9 is a schematic diagram illustrating a contributing resistancegenerated by the AMR effect; and

FIG. 10 is a schematic diagram illustrating a deviation in themagnetization direction of a free magnetic layer owing to a shapeanisotropic magnetic field H_(k).

DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in FIG. 1, a rotation angle sensor according to the presentinvention comprises a planar support (a fixed part) 21, which is made ofa nonmagnetic material and is fixed on a case 20, and a rotor, which isdisposed over the support 21 and has a discoidal magnet 22. The magnet22, which faces the fixed part 21 and is made of, for example, ferrite,is polarized radially. The magnet 22 has a thickness of severalmillimeters and a radius of several centimeters.

A rotary shaft 23 made of a nonmagnetic material is fixed to the rotor,protrudes from the case 20, and is rotatably supported on the case 20.

Substrates K1, K2, K3, and K4, each of which includes twomagnetoresistive elements R1 and R2, as shown in FIG. 4, may be disposedon the support 21 and faces to the magnet 22.

The magnetoresistive elements R1 and R2 may be laminates, as shown inFIG. 6. The laminate may include an antiferromagnetic layer 30 made ofPtMn alloy, a pinned magnetic layer 31 made of NiFe alloy, a nonmagneticmaterial layer 32 made of a nonmagnetic conductive material, such as Cu,and a free magnetic layer 33 made of a NiFe alloy in this order from thebottom.

The external magnetic field (a magnetic flux F from the magnet 22 inFIG. 1) induces a change in the magnetization of the free magnetic layer33. On the other hand, the pinned magnetic layer 31 is magnetized in apredetermined direction by a coupling magnetic field generated betweenthe pinned magnetic layer 31 and the antiferromagnetic layer 30.

While the magnetoresistive elements R1 and R2 shown in FIG. 6 arespin-valve thin film elements, they may be any other laminate structureshaving a first layer, such as the free magnetic layer 33, in whichchanges in magnetization are induced by the external magnetic field, anda second layer, such as the pinned magnetic layer 31, which has a fixedmagnetization direction against the external magnetic field. Thus,changes in the angle between the first layer and the second layer causevariations in the electric resistance of the elements.

The magnetoresistive elements R1 and R2 on the substrates K1, K2, K3,and K4 shown in FIG. 4 have the same laminate structure.

As shown in FIG. 2, each end of the magnetoresistive elements R1 and R2is connected to a lead 40 or 41 made of Au or Cu, from which electriccurrent flows to the magnetoresistive elements R1 and R2.

As shown in FIG. 4, the opposite ends of the leads 40 and 41 areconnected to terminals A-P, which are integrally or separately providedwith the leads 40 and 41.

These terminals A-P are connected to one another as in FIG. 5, andconstitute two Wheatstone bridges.

The structures of the magnetoresistive elements R1 and R2 on thesubstrates K1, K2, K3, and K4 are further described below.

The phrase “X-axis direction” used below means the width direction ofthe substrate K4, and “Y-axis direction” means the depth direction ofthe substrate K4, perpendicular to the X-axis direction.

The substrate shown in FIG. 2 is the substrate K4 shown in the lowerright of FIG. 4. The two magnetoresistive elements R1 and R2 aredisposed on the substrate K4 at a predetermined interval in the Y-axisdirection.

The magnetoresistive element R1 includes an X-axis array 42 and a Y-axisarray 43, which are connected to each other at a boundary S. The X-axisarray 42 shown on the right of the boundary S includes five X-axissegments (1)-(5) parallel to the X-axis, which are spaced at apredetermined interval T2 in the Y-axis direction. The predeterminedinterval T2 is sufficiently smaller than the length L1 of the X-axissegments (1)-(5) and is, for example, between 10 and 20 μm.

Ends 42 a in the same direction of the adjacent X-axis segments ((1) and(2), (2) and (3), (3) and (4), (4) and (5)) are alternately connected toeach other. Thus, the X-axis array 42 has a meandering structure.

The Y-axis array 43 includes five Y-axis segments (6)-(10) parallel tothe Y-axis, which are spaced at a predetermined interval T2 in theX-axis direction. The predetermined interval T2 is sufficiently smallerthan the length L1 of the Y-axis segments (6)-(10).

Ends 43 a in the same direction of the adjacent Y-axis segments ((6) and(7), (7) and (8), (8) and (9), (9) and (10)) are alternately connectedto each other. Thus, the Y-axis array 43 has a meandering structure.

The X-axis array 42 and the Y-axis array 43 are connected at theboundary S to form the single continuous structure of themagnetoresistive element R1.

The lines shown at the boundary S and the ends 42 a and 43 a are onlyprovided for a better understanding, and final products do not have suchlines. The X-axis array 42 and the Y-axis array 43 may be formedsimultaneously by sputtering.

When rotated 90°, the Y-axis array 43 has the same layout as the X-axisarray 42.

The five segments (1)-(5) of the X-axis array 42 and the five segments(6)-(10) of the Y-axis array 43 have the same width T1 and the samelength L1.

Thus, in the absence of the external magnetic field, the X-axis array 42and the Y-axis array 43 will have almost the same electrical resistanceunder energized conditions.

The contributing resistance generated by the AMR effect in themagnetoresistive element R1 will be described below.

A contributing resistance R_(x) generated by the AMR effect in theX-axis array 42 is expressed by the following equation according to thesame theory illustrated in FIG. 9:R _(X) =R _(B0) +ΔR _(B) cos²θ′  (4)wherein, R_(x) is a contributing resistance generated by the AMR effectin the X-axis array 42, R_(B0) is a center resistance, ARB is anamplitude of the electrical resistance change, and θ′ is an anglebetween the current direction and the magnetization direction of thefree magnetic layer 33.

Since the Y-axis segments (6)-(10) is perpendicular to the X-axissegments (1)-(5), the direction of the electric current passing throughthe Y-axis segments (6)-(10) is also perpendicular to that of the X-axissegments (1)-(5).

Thus, a contributing resistance R_(Y) generated by the AMR effect in theY-axis array 43 is expressed by the following equation, in which “ΔR_(B)cos²θ′” is replaced by the “ΔR_(B) cos²(θ′+90)”, that is, “ΔR_(B)sin²θ′”:R_(Y)=R_(B0)+ΔR_(B) sin²θ′  (5)wherein, R_(Y) is a contributing resistance generated by the AMR effectin the Y-axis array 43, R_(B0) is a center resistance, ΔR_(B) is anamplitude of the electrical resistance change, and θ′ is an anglebetween the current direction and the magnetization direction of thefree magnetic layer 33.

Equation 4 plus equation 5 gives the following equation:R _(X) +R _(Y)=2R _(B0) +ΔR _(B)  (6)because of cos²θ′+sin²θ′=1.

As shown in equation 6, both cos²θ′ and sin²θ′ are precluded from thecontributing resistance (R_(X)+R_(Y)) generated by the AMR effect in themagnetoresistive element R1, and thereby the contributing resistance canbe limited to predetermined values. This cancels the electricalresistance change caused by the AMR effect, thus reducing the waveformdistortion of the output voltage.

It should be noted again that equations 4 to 6 hold when the X-axisarray 42 and the Y-axis array 43 in the magnetoresistive element R1include five segments (1)-(5) and five segments (6)-(10), respectively,all the segments having the same width T1 and the same length L1, theX-axis array 42 and the Y-axis array 43 having the same R_(B0) and thesame ΔR_(B).

Thus, when the X-axis segments and the Y-axis segments are different innumber, the X-axis 42 and the Y-axis array 43 will have different R_(B0)and different ΔR_(B).

Even in such a situation, when ΔR_(B) cos²θ′ in equation 4 (denoted byΔR_(B1) cos²θ′) and ΔR_(B) sin²θ′ in equation 5 (denoted by ΔR_(B2)sin²θ′) are added together, changes in the sum (ΔR_(B1) cos²θ′+ΔR_(B2)sin²θ′) caused by the variation of θ′ can be smaller than those ofconventional elements, and thereby changes in the contributingresistance generated by the AMR effect can be reduced.

Reduction in the shape anisotropic magnetic field H_(k) is describedbelow.

A reference shape anisotropic magnetic field H_(k) (equals to 1) is setup with conventional magnetoresistive elements 2 and 3 that includesegments having a length of 220 μm and a width of 20 μm, as shown inFIG. 7, on a substrate having sizes of 700 μm×700 μm in the X-axisdirection and in the Y-axis direction.

Then, the width T1 and the length L1 of the magnetoresistive elements R1and R2 in FIG. 2 are adjusted to have the same electrical resistance (inthe absence of the external magnetic field) as the magnetoresistiveelements 2 and 3. Changes in the shape anisotropic magnetic field H_(k)of the magnetoresistive element R1 and R2 are then determined relativeto the reference H_(k) (Table 1). TABLE 1 Width (μm) 10 15 20 28 30 4050 Length 550 0.4 (11) (μm) 440 0.5 (11) 330 0.67 (11) 305 0.71 (10.9)220  1 (11) 165 1.33 (11) 114 0.66 (4.1)  110   2 (11) 0.95 (5.5) 600.85 (3)   45 1.14 (3)  30 1.71 (3) 

Values in parentheses are the ratio of length to width. This value is 11at the reference H_(k), in which the length is 220 μm and the width is20 μm.

Table 1 shows that the shape anisotropic magnetic field H_(k) of themagnetoresistive elements R1 and R2 is smaller than the reference H_(k)when the width is 20 μm or more and the length/width ratio is below 11.

Alternatively, the shape anisotropic magnetic field H_(k) of themagnetoresistive elements R1 and R2 is smaller than the reference H_(k)when the width is more than 20 μm and the length/width ratio is 11 orless.

Thus, the segments (1)-(5) and (6)-(10) in the magnetoresistive elementsR1 and R2 according to the present invention have the width T1 of 20 μmor more and the ratio of the length L1 to the width T1 of less than 11,or alternatively have the width T1 of more than 20 μm and the ratio ofthe length L1 to the width T1 of 11 or less, to reduce the shapeanisotropic magnetic field H_(k).

As shown in FIG. 2, the magnetoresistive element R2 has the same layoutas the magnetoresistive element R1, and thus has the same effect asdescribed above.

In addition, as shown in FIG. 4, the magnetoresistive elements R1 and R2on the substrates K1, K2, and K3 have the same layout when themagnetoresistive elements R1 and R2 on the substrate K4 are turned 90°or 180°, and have the same shape and structure as the magnetoresistiveelements R1 and R2 on the substrate K4.

While the magnetoresistive element R1 includes one X-axis array 42 andone Y-axis array 43 in FIG. 2, it may include a plurality of X-axisarrays 42 and a plurality of Y-axis arrays 43. Preferably, the number ofthe X-axis arrays 42 and the number of the Y-axis arrays 43 are thesame. The plurality of X-axis arrays 42 and the plurality of Y-axisarrays 43 may be alternately connected to each other. Alternatively, aseries of X-axis arrays 42 may be connected to a series of Y-axis arrays43.

Preferably, the leads 40 and 41 at the ends of the magnetoresistiveelements R1 and R2 have rounded or chamfered corners 40 a and 41 arather than sharp edges.

Such rounded or chamfered corners prevent electric field fromconcentrating at the corners, suppressing electric discharge from thecorners to other leads or the magnetoresistive elements R1 and R2. Thus,the electrostatic discharge (ESD) resistance can be improved.

Another embodiment according to the present invention will be describedbelow. FIG. 3 shows magnetoresistive elements R3 and R4 disposed on thesubstrate K4 shown in FIG. 4. The magnetoresistive elements R3 and R4may have the same laminated structure as in FIG. 6. The magnetoresistiveelement R3 includes X-axis segments (1), (3), (5), (7), (9), and (11)(hereinafter referred to as merely “X-axis segments (1)”)) parallel tothe X-axis and Y-axis segments (2), (4), (6), (8), (10), and (12)(hereinafter referred to as merely “Y-axis segments (2)”)) parallel tothe Y-axis. Each of the Y-axis segments (2) is connected to eachvertical surface 50 of the X-axis segments (1), and each of the X-axissegments (1) is connected to each horizontal surface 51 of the Y-axissegments (2). Thus, the X-axis segments (1) and the Y-axis segments (2)are alternately connected to each other, forming a meandering shape. Thelines shown at the ends 50 and 51 are only provided for a betterunderstanding, and the ends 50 and 51 cannot be seen in the finalproducts. The X-axis segments (1) and the Y-axis segments (2) may beformed simultaneously by sputtering.

The magnetoresistive element R3 includes three rows. The X-axis segments(1) and the Y-axis segments (2) are alternately connected to each otherto form a first row that extends to the left on the drawing. A secondrow extends from the left end of the first row to the right on thedrawing. A third row extends from the right end of the second row to theleft on the drawing. The second row and the third row also include thealternating combination of the X-axis segments and the Y-axis segments.

The X-axis segments (1) and the Y-axis segments (2) have the same widthand the same length in FIG. 3.

Since the magnetic elements R3 and R4 have continuous structures of thethree rows that include the same number of X-axis segments and Y-axissegments all having the same width and the same length, equations 4 to 6hold in this case. Since changes in the contributing resistancegenerated by the AMR effect can be cancelled, the waveform distortion ofthe output voltage can be reduced, independent of the variation of θ′.

The length of the row in FIG. 3, which is the length of a centerlineshown in the third row, corresponds to the length L1 of the X-axis array42 and the Y-axis array 43 in FIG. 2. The width of the X-axis segments(1) and the Y-axis segments (2) in FIG. 3 corresponds to the width T1 inFIG. 2.

Leads 40 and 41 have rounded or chamfered corners 40 a and 41 a.

The magnetoresistive elements R1 to R4 may have any shape, includingthose given in FIGS. 2 and 3.

To limit the contributing resistance generated by the AMR effect to apredetermined value independent of the variation of θ′, themagnetoresistive element may have any structure that includes the samenumber of X-axis segments and Y-axis segments all having the same widthand the same length, the X-axis segments being spaced at a predeterminedinterval in the Y-axis direction, the Y-axis segments being spaced at apredetermined interval in the X-axis direction.

An angle sensor according to the present invention detects a tilt angleor a rotation angle in any applications, including general industrialmachinery, industrial robots, medical equipment, construction machinery,excavators, measuring equipment, transportation equipment, automobiles,and ships. For example, the angle sensor can be used as a rotation anglesensor of a steering wheel in an automobile.

1. An angle sensor comprising: a magnetoresistive element that includesa pinned magnetic layer having a fixed magnetization direction and afree magnetic layer having a magnetization direction that varies inproportion to an external magnetic field; a substrate for supporting themagnetoresistive element; and a rotor that forms a magnetic field andfaces the magnetoresistive element, wherein the magnetoresistive elementincludes a plurality of X-axis segments that extend in an X-axisdirection being the width direction of the substrate, and a plurality ofY-axis segments that extend in a Y-axis direction being the depthdirection of the substrate, the X-axis segments and the Y-axis segmentshaving the same length and width, and being alternately connected toeach other to form a single continuous structure.
 2. The angle sensoraccording to claim 1, wherein each of the Y-axis segments is connectedto each vertical surface of the X-axis segments, and each of the X-axissegments is connected to each horizontal surface of the Y-axis segments,so that the magnetoresistive element forms at least one row extending inthe X-axis direction or the Y-axis direction, and each end of the rowsin the same direction is alternately connected to form a singlecontinuous structure, when said at least one row comprises a pluralityof rows.
 3. An angle sensor comprising: a magnetoresistive element thatincludes a pinned magnetic layer having a fixed magnetization directionand a free magnetic layer having a magnetization direction that variesin proportion to an external magnetic field; a substrate for supportingthe magnetoresistive element; and a rotor that forms a magnetic fieldand faces the magnetoresistive element, wherein the magnetoresistiveelement includes a plurality of segments in an X-axis direction beingthe width direction of the substrate and a plurality of segments in aY-axis direction being the depth direction of the substrate, the X-axissegments being spaced at a predetermined interval in the Y-axisdirection, the Y-axis segments being spaced at a predetermined intervalin the X-axis direction, the X-axis segments and the Y-axis segmentsbeing the same in number, length, and width.